CoAP is a lightweight client/server application protocol which supports a Representational State Transfer(REST) paradigm: clients perform operations on the resources stored in a server.
This is done through a request/response exchange, and only four request types exist:
GET(i.e., retrieve the content of the resource), POST(i.e., create a new resource), PUT(i.e., update the content of an existing resource), DELETE(i.e., remove a
resource).
Resources are identified through Unique Resource Identifiers (URI), with the same syntax as HTTP,e.g.: coap://coap-server.com/resource/name.
To facilitate the implementation on small devices with low computational/memory capabilities, a number of design choices have been considered in CoAP, including: